I just looked at a spare set of federal mogul mains, 2151 to 2154 for the late 55 to 62 motor. 2151,2 and 4 all have a dowel on one bearing shell and a tang on the other to locate the bearing. 2153 is the thrust bearing. I am not sure I have ever used bearings that did not have these locators. I have always stayed away from the early 55 and earlier blocks just to avoid messing with the shims. do these motors not have locators for the mains?
